Method of manufacturing optical semiconductor integrated circuit device

Abstract

In an existing optical semiconductor integrated circuit device, a silicon nitride film that is an anti-reflection film is used as an etching stopper film at the etching of an insulating film and by means of wet etching the insulating film is removed once for all. Accordingly, there is a problem in that the processing accuracy is poor. In an optical semiconductor integrated circuit device according to the present invention, after a multi-layered wiring layer is formed on a top surface of a silicon substrate, an insulating layer on a top surface of an anti-reflection film of a photodiode is removed by means of dry etching. At this time, a polycrystal silicon film is used as an etching stopper film. Thereby, in the photodiode according to the invention, although the dry etching is used, since a silicon nitride film that is an anti-reflection film is not over-etched, the dispersion of film thickness thereof can be inhibited from occurring. As a result, a photodiode according to the present invention can realize an improvement in the sensitivity of incident light and a miniaturization structure can be realized.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method of manufacturing an optical semiconductor integrated circuit device having a photodiode and intends to eliminate variation of thickness of insulating film laminated on the photodiode and thereby to improve the sensitivity of the photodiode.[0003]2. Description of the Related Art[0004]In a photodiode for blue laser, a transparent package absorbs energy of incident light to cause the burning of the package. Accordingly, for an IC package, a hollow package has to be adopted. As a result, an insulating film on a photodiode formation region is exposed to air in the hollow package. The reflection of incident light at a surface of the insulating film depends on a thickness of the insulating film. That is, a problem is known in that the sensitivity of the photodiode fluctuates as the film thickness of the insulating film fluctuates.[0005]In this connection, as a countermeasure against t...

AI Technical Summary

Benefits of technology

The present invention provides a method of manufacturing an optical semiconductor integrated circuit device with improved processing accuracy and miniaturization capabilities. The method includes preparing a semiconductor substrate, forming a semiconductor layer on the substrate, and forming a photodiode on the semiconductor layer. An insulating layer is then removed from the photodiode formation region using a dry etching process with a polycrystal silicon film as an etching stopper film. This method ensures accurate insulating layer removal and minimizes damage to the underlying structures, resulting in improved sensitivity and reduced fluctuation in thickness of the antireflection film.

Problems solved by technology

That is, a problem is known in that the sensitivity of the photodiode fluctuates as the film thickness of the insulating film fluctuates.

Accordingly, when the insulating film is removed by etching, since the etching proceeds in a horizontal direction to a surface of the substrate, there are problems in that a desired structure can be obtained with difficulty and the processing accuracy is poor.

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